1. Field of the Invention
The present invention relates to a process for washing and sterilising food products, particularly vegetables, and relevant apparatus.
More specifically, the invention concerns a process of the above kind, particularly studied and realised for realising an innovative vegetable products industrial washing line, permitting eliminating use of sodium hypochlorite without lowering safety hygienic standards or increasing drinkable water consumption.
2. Description of the Prior Art
As it is well known, many apparatuses or systems exist for washing vegetables, mainly in the industrial field.
Among these, it is possible mentioning some, such the described in patent application WO2004095953 A2, concerning a foodstuff disinfection process, said foodstuffs being washed in presence of ozone, oxygen, carbon hydroxide, argon, ultraviolet light, ultrasound, until reaching a vacuum step. Said process has the main advantage of carrying out a cold sterilisation.
Japanese patent application JP 2002345400 A describes an apparatus for maintaining vegetables, fruit and like freshness. Said apparatus comprises an ultraviolet irradiation unit within a containment chamber wherein a suitable atmosphere is maintained. Furthermore, said apparatus comprises a unit for humidification during ultraviolet irradiation, so as to generate ozone within said chamber. A suction unit removes ozone and ethylene produced during this step.
Japanese patent application JP 10174552 concerns a washing and disinfection process for fruit and/or vegetables, mainly comprising the following steps:                washing said fruit and/or vegetables within acid or alkaline water within a container, using at the same time ultrasound waves emitted by an ultrasound generator;        cutting said fruit and/or vegetables by cutting means under an oxidising gas atmosphere, such as ozone, ultraviolet radiation and vapour at a pressure lower than vapour saturation pressure;        packaging said cut fruit and/or vegetables by a packaging unit in presence of vapour or gas with nitrogen and carbon hydroxide at a pressure lower that vapour saturation pressure.        
Finally, Japanese patent application JP 10117948 A concerns a process for washing fruit and vegetables, mainly comprising the steps of washing said fruit and/or vegetables in presence of ultrasounds, said ultrasounds being obtained by an ultrasound generator. Washed fruit and/or vegetables are then subjected to ultraviolet irradiation by germicide lamp, in order to obtain a sterilisation.
In order to make said ultraviolet irradiation, a reflector is included within a container. Finally, a container-cleaning device is provided.
Main problem of the above described systems, as well as of other similar known systems, is that the use sanifying products such as sodium hypochlorite, ozone, peroxides and like that, mixed in high concentration with washing water, permit limiting risks of bacterial pollution and ensure a good protection level against pollution of foodstuff by pathogen agents.
However, use of these products has been always more limited in the last years, mainly due to their toxicity. For example, starting from 2007 their use will be prohibited in Europe according to specific European Union rules.
On the basis of the present technology, these new limits will surely induce a high increase of water consumption and therefore a higher volume of outlets to be subjected to treatment, higher working costs and a remarkable environmental impact.
Another technical problem of the standard systems is that, as it is well known to those skilled in this field, by pasteurising and sterilisation techniques, some basic nutritional components are modified or even completely destroyed (e.g. vitamins).